body {
    margin: 0;
    padding: 0;
    /* 背景颜色渐变 */
    background: linear-gradient(to bottom, #8abfef, #cee1f1);
}

div {
    /* 默认水平居中，设置为容器 */
    display: flex;
    text-align: center;
    justify-content: center;
}

/* 导航栏 */
.main_menu {
    height: 68px;
    background-color: #333333;
    position: fixed;
    width: 100%;
    top: 0;
    z-index: 999;
}

.main_menu #logo {
    width: 200px;
}

.main_menu #logo img {
    height: 50px;
    margin: 9px auto;
}

.main_menu ul, .main_menu li {
    list-style-type: none;
    margin: 0 0;
    padding: 0;
    background-color: #333333;
}

/* 导航栏横向布局 */
.main_menu ul li {
    display: block;
    float: left;
}

.main_menu ul li a {
    display: block;
    color: white;
    width: 160px;
    height: 28px;
    padding: 20px 0;
    font-size: 20px;
    font-weight: bold;
    text-decoration: none;
}

/* 导航栏鼠标移上去后修改颜色 */
.main_menu ul li a:hover {
    background-color: #111111;
}

/* 下拉菜单按钮 */
.main_menu .drop_button {
    background-color: #4CAF50;
    color: snow;
    width: 160px;
    padding: 20px 0;
    font-size: 21px;
    font-weight: bold;
    border: none;
    cursor: pointer;
}

/* 当下拉内容显示后修改下拉按钮的背景颜色 */
.main_menu .dropdown:hover .drop_button {
    background-color: #3e8e41;
}

/* 定位下拉内容 */
.main_menu .dropdown {
    position: relative;
    display: inline-block;
}

/*  下拉内容 (默认隐藏)  */
.main_menu .dropdown-content {
    display: none;
    text-align: center;
    position: absolute;
    min-width: 160px;
    background-color: #64c967;
    box-shadow: 0 8px 16px 0 rgba(0, 0, 0, 0.2);
}

/*  下拉菜单的链接  */
.main_menu .dropdown-content a {
    color: #111;
    font-size: 16px;
    line-height: 28px;
    display: block;
}

/*  鼠标移上去后修改下拉菜单链接颜色  */
.main_menu .dropdown-content a:hover {
    background-color: #a8e7a8;
}

/*  在鼠标移上去后显示下拉菜单  */
.main_menu .dropdown:hover .dropdown-content {
    display: block;
}

.head_portrait {
    width: 60px;
    margin: -18px 5px;
}

.head_portrait_button {
    width: 80px !important;
}

.banner {
    display: block;
    position: absolute;
    width: 100%;
    height: 500px;
    margin-bottom: 40px;
}

.box, .box img {
    position: absolute;
    width: 100%;
    height: 500px;
    max-width: 100%;
    top: 0;
    left: 0;
}

.circle {
    width: 200px;
    height: 14px;
    position: absolute;
    bottom: 15px;
    left: 50%;
    margin-left: -100px;
    text-align: center;
    cursor: pointer;
}

.circle b {
    display: inline-block;
    width: 14px;
    height: 14px;
    background-color: #000;
    border-radius: 50%;
    margin: 3px 5px;
}

.circle .current {
    background-color: #fff;
}

.btn {
    position: absolute;
    top: 50%;
    width: 40px;
    height: 50px;
    margin-top: -25px;
    background-color: rgba(255, 255, 255, .7);
    text-align: center;
    line-height: 40px;
    font-size: 50px;
    cursor: pointer;
}

.left {
    left: 0;
}

.btn img {
    width: 30px;
    margin: 5px 5px;
}

.right {
    right: 0;
}

.body_top {
    margin: 40px auto 0 auto;
    height: 400px;
}

.body_top .body_top_left {
    width: 500px;
    background-color: snow;
}

.body_top .body_top_left img {
    width: 450px;
    height: 360px;
    margin: 20px auto;
}

.body_top .body_top_right {
    width: 900px;
    background-color: #bababa;
    border: 2px solid #333333;
    box-sizing: border-box;
    display: block;
    flex-direction: column;
}

.body_top .body_top_right .content_top {
    width: 896px;
    height: 64px;
    background-color: #868686;
}

.body_top .body_top_right .content_top span {
    color: black;
    font-size: 35px;
    font-weight: bold;
    line-height: 64px;
}

.body_top .body_top_right .content div {
    width: 300px;
    height: 332px;
    display: block;
}

.body_top .body_top_right .content div ul {
    list-style-type: none;
    margin: 0 0;
    padding: 0;
}

.body_top .body_top_right .content .title {
    font-size: 27px;
    font-weight: bolder;
    margin: 25px auto 30px;
    display: block;
}

.body_top .body_top_right .content ul li {
    padding: 4px 80px;
}

.body_top .body_top_right .content li a {
    font-size: 25px;
    line-height: 33px;
    color: black;
    text-decoration: none;
}

.body_top .body_top_right .content ul li img {
    width: 24px;
    vertical-align: middle;
}

.body_bottom div {
    margin: 40px 0 0 0;
    width: 700px;
    height: 456px;
    background-color: #333333;
    display: block;
    float: left;
}

.body_bottom div a {
    text-decoration: none;
}

/* 鼠标移上去后修改颜色/图片放大/阴影 */
.body_bottom div a:hover {
    background-color: #212121;
    display: block;
    box-shadow: 0 15px 20px 0 rgba(51, 51, 51, 0.5);
}

.body_bottom img {
    width: 700px;
    height: 400px;
    transition: all 1s;
}

.body_bottom img:hover {
    transform: scale(1.03);
}

.body_bottom div span {
    height: 52px;
    font-size: 35px;
    color: snow;
    display: block;
}

.footer {
    margin: 90px 0 0 0;
    height: 130px;
    background-color: #fffafa;
}

.footer span {
    display: initial;
    margin: 40px;
    padding: 0;
    font-size: 20px;
}